Bowling pins most often are set up in a 10-pin configuration that forms an equilateral triangular pattern. In the early days of bowling, the pins were set up and removed by hand. Today, pin removal and setup is performed by mechanical pinsetters.
Today’s automatic pin-setting machines are made to store two sets of pins, each numbered from 1 to 10, for a total of 20 pins. On the initial roll of the bowling ball, all 10 pins are be set up on the alley in the shape of an equilateral triangle. When the bowler rolls the ball, camera sensors along the alley detect which pins have been knocked down by the bowling ball. This information is transmitted to the mechanical pinsetter. The machine then picks up the standing pins, sweeps away the downed pins and resets in place the pins that were not knocked down. The bowler rolls the second ball and attempts to knock down the remaining pins. Once again, the camera sensors relay the information about which pins were knocked down back to the mechanical pinsetter and the machine tabulates the bowler's total score. This process continues for a total of 10 frames for each person who is bowling.